This research seeks to provide experimental animal models of two common human visual disorders. The knowledge gained from these studies will have direct application to the prevention, diagnosis and treatment (including rehabilitation) of people with these developmental disorders. A set of experiments will investigate the effects of visual axis misalignment (strabismus) during development on the cortical physiology of kittens. Single cell and evoked potential recording techniques will be used to examine the time course of the sensitive period for strabismus, the ways kittens adapt successfully to the harmful effects of concomitant strabismus and the potential for recovery from strabismus. Other studies will seek evidence for changes in the visual acuity or visual fields of strabismic kittens. This group of studies will provide a systematic analysis of the full range of cortical deficits caused by strabismus and will increase our understanding of the physiological bases of such clinical anomalies as strabismic amblyopia, anomalous correspondence and decreased stereoacuity. A second series of experiments will examine the role of visual experience in the development of the optokinetic nystagmus (OKN) reflex in the cat. These experiments will assess quantitatively the development of OKN eye movements in normal kittens and in each eye of monocularly deprived kittens. Other studies will examine the role of the visual cortex in mediating OKN in these animals and the extent to which the sensitive periods for disrupting OKN and altering cortical physiology coincide. The data from these studies will bear directly on the physiological mechanisms underlying OKN deficits in humans with amblyopia.